With a sharp increase in the demand for electric power, much attention has recently been paid to generating electric power from renewable energy such as solar light, bio-energy, wind power, geothermal heat, marine resources, waste energy, etc., in addition to the existing fossil fuels such as coal, oil, etc. Research has been actively conducted on solar cells that convert solar energy into electric energy among renewable energy resources. In a solar light generation system using a solar cell, mechanical and chemical actions do not occur during conversion of solar energy into electric energy. Thus, the solar light generation system has a simple structure and thus hardly requires maintenance. When the solar light generation system is installed, the system has a long lifetime and is safe and echo-friendly.
A solar cell includes a cell on which solar light is incident, and generates electric power using the characteristics of the cell that generates electric power by a photoelectric effect when solar light is incident thereon. Recently, research has been actively conducted to increase the efficiency of generating electric power using a solar cell. For example, research has been actively conducted to decrease the reflectivity of solar light to be incident on a cell or increase an incidence rate of solar light incident on cells when the cells have the same size. However, when the thickness of an anti-reflection film formed on a surface of the cell is not uniform, an open-circuit voltage decreases and thus a fill factor decreases. Accordingly, there is a need to develop a technique of solving the problems.